Micobiota de plantas donadoras y hongos filamentosos contaminantes del establecimiento in vitro de cinco especies forestales.

Although protocols to propagate large numbers of woody species by in vitro culture have been developed, microbial contamination of explants is a fundamental problem which limits its application. The objectives of this study were: to identify the donor plant mycobiota and to identify filamentous fungi contaminants at the establishment phase of mahogany, teak, majagua, pine and cedar. Explants of donor plants were placed in moist chamber and were prepared to direct optical microscope of fungal growth. Cultural characteristics and morphological were taken into account to identify filamentous fungi contaminants in the establishment phase. Frequency of all genera identified was determined. Eleven genera of filamentous fungi in donor plants and twenty genera in the establishment of forest species were identified. The genera Botryodiplodia, Cephalosporium, Diplodia, Dreschlera, Geotrichum, Gloeosporium Helminthosporium, Memnoniella, Oidiodendron and appeared only during establishment phase. Others such as Alternaria, Aspergillus, Cercospora, Curvularia, Cladosporium, Colletotricum, Fusarium, Nigrospora, Penicillium and Pestalotia were detected in donor plants and during establishment phase. This indicates that the possible source of contamination was the initial explant. The most frequent genera were Botryodiplodia in teak, Nigrospora in majagua and Alternaria in pine, cedar and mahogany. A phytosanitary plan of defence for donor plants was developed. The plan included systemic and contact fungicides whose spectrum of activity covered the identified genera of fungi. [ABSTRACT FROM AUTHOR]